- 15" Laptop
- Spray jacket
- Possibly a third water bottle (I have 2 on the frame, which combined carry 1.6L)
- Yellow-tint glasses for low-light riding
- In the winter months, arm and leg warmers, neck roll and long-fingered gloves
- iPod
- A4 notepad plus pen/pencil
- Possibly a lock for the bike
I think I have two options. The first option (which I am 99% sure won't fly) is to ride my old flatbar bike, The Noble Steed, with panniers. The problem with this is that the reason I replaced The Noble Steed is because it's too big for me and the incorrect fit resulted in a hip injury that took months to resolve. As a test run, I rode The Noble Steed around 40Km the other day and woke up the next day with a dull ache in my hip. As appealing and convenient as the panniers are, I don't think I can ride The Noble Steed on a regular basis.
The second option is to ride The Beast, the bike that replaced The Noble Steed (a Cannondale Synapse 4 Feminine road bike). The Beast fits me perfectly and hasn't given me a hint of pain. Also, it rides like a dream. But The Beast cannot take panniers, so I need to come up with some other solution.
There is a third option, of course - N + 1.

Does anyone have suggestions for a waterproof backpack that can carry my laptop safely, as well as my other crap? I know there's lots of options out there, but I'd like to hear from people who are regularly commuting with a backpack, and what they'd recommend. I'd also like to know if the backpack introduced any discomfort/pain by virtue of putting weight on your back.
Thanks,
Max
